bombmaster

I also have a very loud harmonic or droning sound. This is a significant flutter coming from the speakers and subwoofer. It is happening at neutral throttle or deceleration at 1200-1500 RPM. Very annoying. It just started. ***UPDATE*** Just discovered it was a couple of business cards I had stuffed up in the visor. It was obviously playing havoc on the ANC microphones. Whoop! Whoop! all better now. The noise was so horrible and loud it about makes you want to climb out of the cab. Hope this helps anyone else trying to troubleshoot their low drone sound.